1. Field of the Invention
The present invention relates to a transformer.
2. Description of the Related Art
In related art, a high-voltage generating transformer is provided in which a pair of a primary winding and a secondary winding and a rectifier circuit are integrated with each other. An output voltage of the transformer is determined by an input voltage and a turns ratio between the primary winding and the secondary winding.
Hence, in order to obtain a high-voltage power when the input voltage on the primary side is low, a high turns ratio is necessary, so that the number of turns of the primary winding is decreased and the number of turns of the secondary winding is increased.
However, since the number of turns of the primary winding may not be made smaller than one, when a turns ratio of 1,000 is necessary, for example, the number of turns of the secondary winding is 1,000 or larger. In practice, the number of turns of the primary winding is larger than one, and therefore the number of turns of the secondary winding is much larger.
An increase in the number of turns of the secondary winding involves an increase in distributed capacitance within the winding, and a loss becomes greater as frequency of operation is increased.
Proposed to avoid this are a constitution in which a secondary winding is divided into a large number of secondary windings to form a multilayer winding (layer winding), rectifiers are respectively connected to the divided secondary windings, and the rectifiers are connected in series with each other to obtain a high voltage, and a constitution in which a voltage multiplier rectifier circuit is used as a rectifier circuit.
However, such constitutions invite an increase in size of the transformer and an increase in the number of parts of the rectifier circuit, and are thus disadvantageous in reducing size and cost and securing reliability.
In addition, a transformer is proposed in which a primary winding is divided into a plurality of primary windings for a single secondary winding, and the plurality of primary windings are connected in parallel with each other to thereby obtain a high-current output while achieving miniaturization (see Japanese Patent Laid-Open No. 2002-367837).